title: Biological Control of the Root-Knot Nematode Meloidogyne javanica by Trichoderma harzianum.
abstract: ABSTRACT The fungal biocontrol agent, Trichoderma harzianum, was evaluated for its potential to control the root-knot nematode Meloidogyne javanica. In greenhouse experiments, root galling was reduced and top fresh weight increased in nematode-infected tomatoes following soil pretreatment with Trichoderma peat-bran preparations. The use of a proteinase Prb1-transformed line (P-2) that contains multiple copies of this gene improved biocontrol activity in the greenhouse experiments compared with the nontransformed wild-type strain (WT). All the Trichoderma strains showed the ability to colonize M. javanica-separated eggs and second-stage juveniles (J2) in sterile in vitro assays, whereas P-2 also penetrated the egg masses. This protease-transformed line presented the same nematicidal and overall proteolytic activity as the WT in in vitro tests in which concentrated soil extracts from Trichoderma-treated soils immobilized the infective J2. However, the J2 immobilization and proteolytic activities of both P-2 and the WT were higher than those obtained with strain T-203. Characterization of the activity of all Trichoderma strains soil extracts on J2 showed that it was heat resistant and restricted to the low-molecular-weight fraction (less than 3 kDa). It is suggested that improved proteolytic activity of the antagonist may be important for the biological control of the nematodes.
authors.forename: E
authors.initials: E
authors.lastname: Sharon
authors.forename: M
authors.initials: M
authors.lastname: Bar-Eyal
authors.forename: I
authors.initials: I
authors.lastname: Chet
authors.forename: A
authors.initials: A
authors.lastname: Herrera-Estrella
authors.forename: O
authors.initials: O
authors.lastname: Kleifeld
authors.forename: Y
authors.initials: Y
authors.lastname: Spiegel